Actually, brand is not the issue.
You may want to read up more on flash photography.
If I am going to buy a flash, I will look at ....
1. Guide Number of the flash.
2. Cost of the flash.
3. TTL compatibility.
4. Manually adjustable flash power. (i.e. 1, 1/2, 1/4, 1/8, 1/16, 1/32 ...)
5. Tilt & Swivel capable flash head.
6. Build quality.
7. Recycle time.
8. Zoom head.
9. Trigger voltage.
Of course, I will not choose a flash with all the stuff mentioned above, but I will use them for comparison. And if someone want to use the Nikon CLS, a higher end Nikon flashes are needed. For me, I'd rather get a flash that will work with the cheap
ebay remote wireless flash trigger.